Apparatus and method for distributing a substance

ABSTRACT

A system for controlling the deposit of liquid, gaseous, and/or particulate solid substances from a staging medium and method of making same is provided. The system comprises a distribution medium for receiving substances, and a containment layer adjacent to the substance distribution medium. The containment layer substantially prevents substance from entering the deposit area until the distribution medium is substantially filled with substance, thereby helping to prevent uneven deposits of the substance.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part of patent applicationSer. No. 09/919,128, entitled “Method for Making Composite Structures,”having Steve Slaughter and John C. Fish as inventors, which applicationis assigned to same assignee as the present application, and is herebyincorporated by reference.

BACKGROUND DESCRIPTION OF RELATED ART

[0002] Generally, vacuum assisted resin transfer molding (VARTM)processes include laying up layers of a material of any unimpregnatedfiber and/or fabric on top of a mold. A vacuum bag is placed about thelay-up and sealed to the mold. A peel ply may be placed on top of thelay-up and between the layers and mold surface to insure that the vacuumbag can be removed from the completed part and that the part can beremoved from the mold. Resin is introduced into the vacuum bag, while avacuum is drawn from beneath the lay-up. This causes the resin to flowthrough the lay-up. Thereafter, the resin flow is terminated and theresin in the assembly is cured. This may require that the resin beheated to curing temperature. To insure even distribution of resin intothe lay-up, a resin distribution medium is placed on top of the lay-up,which is designed to cause the resin to evenly distribute there acrosseliminating resin-starved areas.

[0003] Many types of resin distribution have been proposed. Someinventions describe the use of a perforated film between the lay-up andvacuum bag. Resin is fed from the top through the vacuum bag, throughthe perforated film and into the lay-up. A spring is located at theperiphery of the lay-up, but under the perforated film. The spring iscoupled to a vacuum line, thus providing a channel such that resin canbe more readily transferred into the lay-up. This reference is ofinterest for disclosing the use of a perforated film and the use of aspring to provide a channel to the perforated film. However, a specialperforated film is required and there is still the problem of insuringthat the resin reaches all parts of the perforated film. Otherinventions use a wire mesh as a distribution medium in a vacuum assistedmolding process. However, a wire mesh may not necessarily be made toconform to a complex contoured part. Furthermore, an open mesh may allowresin to flow too freely into the lay-up prior to the wire mesh becomingfilled with resin, thus filling the lay-up near the inlet tube andcreating resin starved area further away from the inlet tube.

[0004] Other techniques use channels placed on the lay-up that act asresin distribution paths and become reinforcements on the finished part.This technique is generally not used on parts that do not requirereinforcement.

[0005] In general terms, the design of the distribution medium includestwo parts: spaced apart lines and an array of raised pillars. In detail,the distribution medium can be a crisscrossed pattern of mono-filamentswith raised segments at the intersection of the mono-filaments; a seriesof spaced apart strips forming a grid structure; or a knitted cloth withraised segments being areas of increased bulk. A central conduit in theform of a spring is positioned over the peel ply and is in communicationwith the resin inlet port and acts as a central distribution line. Othertechniques use the distribution mediums on either side of the lay-up.These distribution mediums are specialized products and may unduly raisefabrication costs.

[0006] A method also exists wherein multiple layers of fibrousreinforcements are assembled into a desired configuration on a supporttool, with one of the layers of fibrous reinforcement defining a resincarrier fabric (distribution medium) that extends beyond the peripheryof the other layers. The layers of fibrous reinforcements and tool arecovered with a flexible layer to form an envelope that encapsulates thefibrous reinforcements. A vacuum source evacuates air from the envelope.Resin is introduced into the envelope and fibrous reinforcements byusing a flow path through the one layer used as the resin carrier layer.After the fibrous reinforcements have been impregnated, the resin flowis terminated and the resin is cured. What is really happening is thatan additional fibrous layer is added to the fiber reinforcements makingup the part that extends there beyond and over flow channels at theperiphery of the tool. In one embodiment, this extra fibrous layer isseparated from the “part” by a release or peel ply. In a secondembodiment, the fibrous layer is integral with the part. Thisdistribution medium is designed for use in a process where the resin isintroduced from the peripheral edges of the lay-up.

[0007] A system also exists wherein a pair of preforms with differentpermeabilities are installed in a mold separated by a separation layer.Different resins are injected into each preform by the vacuum assistedresin transfer method. The key to this process is the use of aseparation layer having permeability lower than the permeability ofeither of the fiber preforms.

[0008] Another invention uses a dual bag within a bag concept. Both bagsare sealed to the mold surface with the lay-up within the inner bag. Theouter bag incorporates protrusions. A vacuum is first drawn from betweenthe inner and outer bag. This forces the protrusions into the inner bagcreating a pattern of channels. A vacuum is then drawn from between themold surface and inner bag. Resin is then flowed into the lay-up throughthe channels. Thus the inner bag acts as a resin distribution medium.This apparatus requires a custom vacuum bag, which may raise fabricationcosts.

[0009] Other devises in the general area of substance distributionprovide systems wherein substance held in a reservoir is released to thesurface of an applicator by rupturing a substantially fluid-imperviousbarrier layer in an interior cavity. The pressure provided to rupturethe barrier is provided by manually squeezing and the material is thenspread onto a third surface with the applicator. The apparatus does notcontemplate a direct flow of material through the ruptured barrier ontothe ultimate surface or build-up of pressure through a change inatmospheric pressure in the filling apparatus or through the weight ofaccumulating material.

SUMMARY

[0010] An apparatus for controlling the flow of liquid, gaseous, orparticulate solid substances from a substance distribution system andmethod for making same is provided. In some embodiments, a system forcontrolling the flow of a substance includes a distribution medium forreceiving the substance, and a containment layer adjacent to thedistribution medium. The containment layer substantially prevents thesubstance from flowing until the distribution medium is substantiallyfilled with substance.

[0011] In an alternate embodiment, a method for controlling the flow ofa substance includes placing a distribution medium adjacent to acontainment layer; introducing the substance into the distributionmedium; configuring the containment layer to substantially prevent thesubstance from flowing from the distribution medium until the substancedistribution medium is substantially filled with substance; andreconfiguring the containment layer to allow the substance to flow to anintended destination.

[0012] In still another embodiment, a resin distribution system includesa resin distribution medium for receiving the resin. The resindistribution medium includes a first principle side facing the resininflow and a second principle side facing the mold surface. A resincontainment layer is positioned adjacent to the resin distributionmedium. The resin containment layer is configured to substantiallyprevent the resin from entering the lay-up until the resin distributionmedium is substantially filled with resin.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Embodiments of the present invention may be better understood,and their numerous objects, features, and advantages made apparent tothose skilled in the art by referencing the accompanying drawings. Theuse of the same reference symbols in different drawings indicatessimilar or identical items.

[0014]FIG. 1A is a cross-sectional view of an embodiment of a system fordistributing layers of one or more substances.

[0015]FIG. 1B is a cross-sectional view of another embodiment of asystem for ting layers of one or more substances.

[0016]FIG. 2 is an exploded perspective view of the system illustratedin FIG. 1A.

[0017]FIG. 3 is an enlarged perspective view of an embodiment of thecontainment layer, wherein the containment layer is made of materialthat melts. FIG. 4 is an enlarged perspective view of another embodimentof the containment layer, wherein the containment layer is made of aperforated heat shrinkable material.

[0018]FIG. 5 is an enlarged perspective view of another embodiment ofthe containment layer, wherein the containment layer is made of a highlyperforated or highly embossed, frangible material.

[0019]FIG. 5A is partial enlarged view of FIG. 5.

DETAILED DESCRIPTION

[0020] Referring to FIGS. 1A and 2, an embodiment of a distributionsystem 10 for controlling and distributing the flow of liquid, gaseous,and particulate solid substances is shown including distribution medium22 and containment layer 24. Distribution medium 22 includes a firstprinciple side facing an inflow of substance and a second principle sidefacing containment layer 24. Containment layer 24 is designed tosubstantially prevent substance from flowing to an intended destinationuntil distribution medium 22 is substantially filled with substance.

[0021] In some embodiments, distribution system 10 can be utilized tofabricate composite materials. System 10 includes mold 12 and moldsurface 14. For purposes of illustration a flat mold surface 14 isshown, however, mold surface 14 can be curved, can include a movingconveyor belt, or any other surface for evenly distributing resin overone or more layers of material 16A through 16D to form lay-up 16. Insome embodiments, peel ply layers 18A, 18B can be positioned adjacentone or both of the outer sides of lay-up 16. Peel ply layers 18A, 18Bare typically made of a porous material to allow resin to easily passthrough without bonding to mold surface 14 or containment layer 24 asresin-impregnated lay-up 16 equilibrates into its final state. In otherembodiments, peel ply layers 18A, 18B may not be included.

[0022] In some embodiments, outer sheet 26, also referred to as a vacuumbag, includes inlet port 28 positioned adjacent distribution system 10and sealed at its marginal edges 30 to mold surface 14 by sealant tape32 or other suitable means to form chamber 34. An example of a sealanttape 32 that can be utilized is Tacky Tape™ manufactured bySchnee-Moorehead, Irving, Tex. Vacuum outlet port 35 can be installedbetween mold surface 14 and marginal edge 30 of outer sheet 26 fordrawing a vacuum in chamber 34.

[0023] In some embodiments, substance enters inlet port 28, while avacuum is drawn from outlet port 35. The vacuum causes outer sheet 26 tocollapse down around distribution medium 22. Without distribution medium22, it would be difficult to evenly distribute resin over lay-up 16, andsubstance starved areas or even voids could be created in the curedlay-up 16. With substance distribution medium 22, however, resin canflow evenly lay-up 16, greatly reducing the chance of forming voids andthe like in the final product.

[0024]FIG. 1B shows another embodiment of distribution system 10 thatinclude vacuum outlet ports 35′ in mold 12. Outlet ports 35′ can bepositioned in one or more locations in mold 12. Portions of outlet ports35′ extending from mold 12 can be fitted to a vacuum source to drawouter sheet 26 to collapse around distribution medium 22 and lay-up 16.In some embodiments, one or more outlet ports 35′ are positioned aroundthe periphery of lay-up 16 in areas where there are likely to be gapsbetween lay-up and outer sheet 26. As many inlet ports 28 and outletports 35′ as necessary can be utilized, thereby enabling distributionsystem 10 to be utilized to fabricate components in a variety of shapesand sizes. Further, a combination of one or more outlet ports 35 (FIG.1A) and outlet ports 35′ can be utilized in the same distribution system10.

[0025] Lay-up 16 can comprise one or more layers of material, such aswoven fiberglass, graphite or other composite reinforcement material.Peel plies 18A and 18B can be made of a material such as coatedfiberglass, which is porous to resin so that resin can easily passthrough without bonding to mold surface 14 or containment layer 24 asthe resin cures. A suitable peel ply material is Release Ease 234TFP,manufactured by Airtech Products, Incorporated, Huntington Beach, Calif.

[0026] In some embodiments of distribution system 10, a materialsuitable for use as outer sheet 26 is impregnated Nylon, which can beobtained from numerous suppliers such as the previously mentionedAirtech Products. When the substance being distributed is resin,distribution medium 22 can be comprised of any suitable material. Forexample, a knitted mono-filament UV stabilized high density polyethylenecan used as distribution medium 22, such as commercially availableSolarGuard™ manufactured by Roxford Fordell Company, Greenville, S.C.Anther suitable product for distribution medium 22 is Colbond 7004manufactured by Colbond, Incorporated, Enka, N.C. Colbond 7004 is arandom orientated, heat fused mono-filament material.

[0027] Referring to FIGS. 1A and 3, in other embodiments, temperaturesensitive containment layer 24A has a melting point such thatcontainment layer 24A dissolves or melts after substance is at leastpartially distributed in distribution medium 22. Once containment layer24A melts, the substance can flow to its intended destination.Distribution system 10 can include means for applying heat totemperature sensitive containment layer 24A. Heating can be done eitherdirectly by means such as raising the ambient temperature, blowingheated air, conducting electricity through a metallic frame, chemicalreaction, or other suitable means. Heat can also be applied to substancecontainment layer 24A by heating the substance before, during, or afterthe substance contacts containment layer 24A. Other materials thatdissolve can be used for containment layer 24A in addition to, orinstead of, containment layers 24A that dissolve when heated.

[0028] In some embodiments, a temperature sensitive containment layer24A includes a meltable substance layer 36 and porous veil material 37.An example of a suitable material for temperature sensitive containmentlayer 24A for use with resin is Blue Max Tak Tu on Reemay (a polyesternon-woven veil), manufactured by The Blue Max Company, Anaheim, Calif.The Blue Max Tak Tu material is a low temperature melting resin 36 thatis applied to a porous veil material 37.

[0029] Referring to FIG. 4, another embodiment of containment layer 24Bincludes a plurality of holes 40 in a heat shrinkable material. Holes 40are a size such that substance will not readily flow there through atambient temperatures. Upon heating, the material of containment layer24B will shrink, causing holes 40 to increase in size, shown in dottedlines and indicated by numeral 40′, allowing substance to flow fromsubstance distribution medium 22. A suitable heat shrinkable materialfor use with resin substances includes Intercept Shrink filmmanufactured by FPM, Incorporated, Brownstone, Me.

[0030] Referring to FIGS. 1, 5 and 5A, in some embodiments, containmentlayer 24C is a porous film 42 includes a plurality of holes or veryclosely spaced perforations 44. The size of the perforations is selectedto prevent or greatly reduce substance flow through substancecontainment layer 24C. Holes 44 having a size such that substance willnot flow there through when a vacuum is drawn to outlet port 35 at afirst rate and will flow there through when a vacuum is drawn fromoutlet port 35 at a higher second rate. Calculating the size of holes 44in substance containment layer 24C can be accomplished as follows. For alayer of substance above substance containment layer 24C, thehydrostatic pressure at the layer is by the equation:

PH=ρhg

[0031] Where: ρ is the density of the substance,

[0032] h is the depth (height) of the substance, and

[0033] g is the gravitational constant

[0034] The “excess pressure” developed by the surface tension of thesubstance and the openings (perforations) in substance containment layer24C can be expressed as:

PE=2 T/d

[0035] where T is the surface tension of the substance and

[0036] d is the perforation diameter (assumes circular perforation)

[0037] The governing equation for substance containment sets thehydrostatic pressure equal to the excess pressure:

ρhg=2 T/d

[0038] Properties of a typical resin, such as Derakane 411 C-50 resin byDow Chemical Company, Midland, Mich. are:

ρ=1265 kg/m3

T=0.032 Newtons/meter

[0039] The maximum perforation size that overcomes the hydrostaticpressure is then:

d=2 T/((hg)=2(0.032)/(1265×h×9.8)

d=0.000005163/h meters.

[0040] Using a typical thickness of a substance distribution medium,where the substance is resin, the substance height becomes 0.00635 m(0.25 in) and the maximum perforation size is:

d _(max)=8.13×10⁻⁴ meters (0.032 in).

[0041] For thicker substance distribution mediums, the maximumperforation size will decrease. Perforations larger than this maximumvalue may not contain the substance during infusion. Similarly, theminimum perforation size can be estimated by equating the excesspressure to the sum of the hydrostatic pressure and the vacuum pressurein the bagged assembly:

ρhg+PV=2 T/d

[0042] where PV will be on the order of one atmosphere. At sea level, PVis approximately 100 kiloPascals (kPa) and dominates the left side ofthe equation above. The minimum perforation size is then estimated by:

d _(min)=2 T/PV=2(0.032)/(100×10³)

d _(min)=6.4×10⁻⁷ meters=2.5×10⁻⁵ inches

[0043] Perforations smaller than this minimum value may not permitsubstance to pass through the substance containment layer 24C undervacuum pressure. The substance containment layer 24C perforation size isthen bounded by:

[0044] 2.5×10⁻⁵ inch<d<0.032 inch

[0045] A suitable material for containment layer 24C for use with resinsubstances is Easy Gardner Tree Wrap having round holes with a 0.015inch diameter or Easy Gardner Weed Block with square holes of a similarsize. Both of these materials are manufactured by Easy Gardner,Incorporated, Waco, Tex. This method of calculation can also be used todesign the perforations for temperature sensitive containment layers 24B(FIG. 4).

[0046] In still other embodiments of distribution system 10 (FIG. 1),containment layer 24 can be comprised of a layer of perforated materialincluding a plurality of embossed holes. Sufficient pressure can beapplied to containment layer 24 to cause the perforations to release andallow the substance to flow once it is distributed in distribution layer22. Distribution system 10 can be modified to include means for applyingpressure to the substance in distribution layer 24 to induce tearing ofthe holes in containment layer 24. Such means include physicallyapplying pressure to the substance, applying vacuum pressure, such as bydrawing a vacuum on chamber 34, or other suitable means. Containmentlayer 24 can also be configured to tear upon application of sufficientweight of the substance. Distribution medium 22 can be configured toallow sufficient substance to accumulate to apply the required weight tocontainment layer 24.

[0047] Other embodiments include containment layer 24 fabricated frommaterials whose porosity properties change under application ofdifferent rates of vacuum, different rates of atmospheric pressure, andvarying heat. Substances that can be distributed with distributionsystem 10 include any amounts of liquid, solid, and/or gaseoussubstances. Distribution layer 22 can be fabricated from any suitablematerial or combination of materials, and can include grids or othersuitable openings to distribute the substance.

[0048] Various embodiments can include two or more distribution systems10 that are configured to allow substances to be combined automaticallyat desired pre-selected time intervals, or upon application of means toat least partially remove containment layer 24 to allow the substance toflow toward its intended destination. For example, containment layer 24in one distribution system 10 can be configured to release the substancewhen activated by an operator. The distributed substance can flow ontoand chemically react with another substance in a second distributionsystem 10. Containment layer 24 can be configured to release thecombined substances either manually or automatically once the chemicalreaction is complete.

[0049] Distribution medium 22 can be configured to accumulate all or aportion of the substance to be distributed by increasing the depth ofthe grid, including side walls around the perimeter of distributionmedium 22, or other suitable structure. Further, distribution system 10can be oriented to allow substance to flow in any desired direction.Additionally, the substance can be forced to flow in any desireddirection through the use pressure, pumps, or other suitable mechanismfor inducing flow through distribution medium 22.

[0050] While the present disclosure describes various embodiments, theseembodiments are to be understood as illustrative and do not limit theclaim scope. Many variations, modifications, additions and improvementsof the described embodiments are possible. For example, those havingordinary skill in the art will readily implement the structures andmethods disclosed herein, and will understand that any processparameters, materials, and dimensions are given by way of example only.The parameters, materials, and dimensions can be varied to achieve thedesired structure as well as modifications, which are within the scopeof the claims. Variations and modifications of the embodiments disclosedherein may also be made while remaining within the scope of thefollowing claims. In the claims, unless otherwise indicated the article“a” is to refer to “one or more than one”.

What is claimed:
 1. A system for controlling the flow of a substancecomprising: a distribution medium for receiving the substance, and acontainment layer adjacent to the distribution medium wherein thecontainment layer substantially prevents the substance from flowinguntil the distribution medium is substantially filled with substance. 2.The system as set forth in claim 1 further comprising: a chamber formaintaining a differential pressure from the prevailing atmosphericpressure, and a source for developing such a differential pressure. 3.The system as set forth in claim 1, further comprising a heat source forapplying heat to the containment layer.
 4. The system as set forth inclaim 3, wherein the heat source includes the substance being appliedpreheated to a specified temperature.
 5. The system as set forth inclaim 3 wherein the substance containment layer has a melting point suchthat the substance containment layer melts upon heating, allowing thesubstance to flow.
 6. The system as set forth in claim 3 wherein thecontainment layer comprises a plurality of holes through a heatshrinkable material, the holes having a size such that substance willnot readily flow there through at ambient temperatures and upon heating,the heat shrinkable material shrinks causing the holes to increase insize, allowing substance to flow from the distribution medium.
 7. Thesystem as set forth in claim 2 wherein the containment layer comprises aplurality of holes, the holes having a size such that substance will notflow there through when a vacuum is drawn to an outlet port at a firstrate and will flow there through when a vacuum is drawn from the outletport at a higher second rate.
 8. The system as set forth in claim 1wherein the containment layer comprises a layer of frangible material,the frangible material includes a plurality of partially perforatedembossed holes which will release and allow the passage of substanceupon application of sufficient pressure.
 9. The system as set forth inclaim 1, further comprising means to apply pressure to the substancewhile the substance is retained in the distribution medium.
 10. Thesystem as set forth in claim 1, wherein the weight of the substanceprovides sufficient force to rupture the containment layer to allow thesubstance to flow to an intended destination.
 11. The system as setforth in claim 1, further comprising a peel ply layer positionedadjacent to the substance.
 12. The system as set forth in claim 1wherein the containment layers is selected from materials whose porositychanges under at least one of the group of: vacuum force, atmosphericpressure, and temperature.
 13. The system as set forth in claim 1,further comprising: an outer sheet positioned around the distributionmedium and the containment layer to form a chamber; and a vacuum outletport positioned to draw a vacuum within the chamber.
 14. The system asset forth in claim 13, further comprising: a mold surface, wherein thevacuum outlet port extends through the mold surface.
 15. The system asset forth in claim 13, wherein the vacuum outlet port extends externallyfrom the outer sheet.
 16. A method for controlling the flow of asubstance: placing a distribution medium adjacent to a containmentlayer; introducing the substance into the distribution medium;configuring the containment layer to substantially prevent the substancefrom flowing from the distribution medium until the substancedistribution medium is substantially filled with substance; andreconfiguring the containment layer to allow the substance to flow to anintended destination.
 17. The method as set forth in claim 16 whereinreconfiguring the containment layer includes varying the pressure on thesubstance after introducing the substance into the distribution medium.18. The method as set forth in claim 16, wherein reconfiguring thecontainment layer includes heating the containment layer.
 19. The methodas set forth in claim 18, wherein the substance containment layer isheated by the substance.
 20. The method as set forth in claim 18,wherein reconfiguring the containment layer includes applying pressureto the substance to rupture the containment layer.
 21. The method as setforth in claim 16, wherein reconfiguring the containment layer includesat least partially dissolving the containment layer.
 22. The method asset forth in claim 16, wherein reconfiguring the containment layerincludes at least partially melting the containment layer.
 23. Themethod as set forth in claim 16, wherein reconfiguring the containmentlayer includes at least partially shrinking the containment layer. 24.The method as set forth in claims 16 further comprising placing a peelply layer adjacent to the intended destination of the substance.
 25. Aresin distribution system comprising: a resin distribution medium forreceiving the resin, the resin distribution medium includes a firstprinciple side facing the resin inflow and a second principle sidefacing the mold surface; and a resin containment layer adjacent to theresin distribution medium, wherein the resin containment layer isconfigured to substantially prevent the resin from entering the lay-upuntil the resin distribution medium is substantially filled with resin.26. The system as set forth in claim 25, further comprising: a moldsurface; an outer sheet placed over the lay-up, and over the resindistribution system, wherein the outer sheet's edges are sealed to themold surface to form a chamber; a resin inlet port in the outer sheet;and a vacuum outlet for drawing a vacuum in the chamber.
 27. The systemas set forth in claim 25 wherein the resin containment layer has amelting point such that the resin can be distributed into the resindistribution medium, and the resin containment layer melts upon heatingof the resin.
 28. The system as set forth in claim 25 wherein the resincontainment layer comprises a plurality of holes through a heatshrinkable material, the size of the holes being such that resin willnot readily flow there through at pre-selected temperatures and uponadjusting the temperature to another pre-selected value, the materialshrinks causing the holes to increase in size, allowing resin to flowfrom the resin distribution medium.
 29. The system as set forth in claim26 wherein the resin containment layer comprises a plurality of holesthere through, the holes having a size such that the resin will not flowthere through when a vacuum is drawn to an outlet port at a first rateand will flow there through when a vacuum is drawn from the outlet portat a higher second rate.
 30. The system as set forth in claim 25 whereinthe resin containment layer comprises a layer of frangible material, thefrangible material including a plurality of partially perforatedembossed holes configured to rupture upon application of sufficientpressure to allow the passage of the resin.
 31. The system as set forthin claim 30, further comprising means to apply pressure to the resinagainst the resin containment layer.
 32. The system as set forth inclaim 30, wherein the weight of the resin provides sufficient pressureto rupture the embossed holes.
 33. The system as set forth in claim 25,further comprising a peel ply layer positioned adjacent to one side ofthe lay-up.
 34. The system as set forth in claim 33 wherein the peel plylayer is made of a coated fiberglass material.
 35. The system as setforth in claim 28 wherein the size of the holes is based on the densityof the resin and the surface tension of the resin.
 36. The system as setforth in claim 27 wherein the containment layer comprises a meltablesubstance that is applied to a porous veil material.
 37. The system asset forth in claim 28 wherein the layer of perforated heat shrinkablematerial such as Intercept Shrink film manufactured by FPM,Incorporated.
 38. The system as set forth in claim 26, wherein thevacuum outlet port is positioned between the outer sheet and the moldsurface.
 39. The system as set forth in claim 26, wherein the vacuumoutlet port extends through the mold surface.